1. Field of the Invention
The present invention relates generally to an atherectomy device and method for removing or reducing atheromas, and thrombus and plaque from within blood vessels. More specifically, the present invention discloses an improved atherectomy device that uses a distal cutter to remove atherombas, thrombus, and plaque from the walls of vascular vessels.
Coronary and peripheral vascular arteriosclerosis, known also as atherosclerosis, is a common ailment occurring in humans which involves the deposition of fatty-like substances called atheromas or plaque on the walls of blood vessels. When long term plaque build-up reaches the point of nearly totally occluding a vessel, a thrombus (clot)-type attachment can occur resulting in long segments of soft vessel occlusion. Atheromas are most common in the peripheral blood vessels that feed the limbs of the human body and the coronary arteries which feed the heart. Extended thrombus-type occlusions occur primarily in the peripheral blood vessels.
In the past, several methods have been attempted to restore normal blood flow through the affected vessels Traditionally, major surgery was the only practical means of treating occlusions. More recently, there has been substantial success in increasing the size of the flow passages within occluded vessels through the use of a dilation process known as balloon angioplasty. In the environment of extended occlusions, devices such as hot-tip probes have been used to penetrate long occlusions in order to allow subsequent entry of balloon catheters. Such penetration is necessary since angioplasty catheters have difficulty in crossing an extended occlusion on their own.
2. Description of the Background Art
A co-pending application Ser. No. 132,675 (corresponding to EPO publication 163 502) discloses an atherectomy device and method for removing at least a part of an atheroma through the use of a cutting device that is inserted into an artery where an atheroma is located. A cutting edge exposed through a cutout in the side of a substantially cylindrical housing is activated to sever a portion of the atheroma from the walls of the blood vessel. Another co-pending patent application Ser. No. 045,916 filed May 1, 1987, discloses an atherectomy device particularly suited for the removal of relatively short severe occlusions. The atherectomy catheter includes a cutter assembly having an annular cutter that is extendable beyond the confines of its housing. An expandable basket or other suitable means is provided distally of the cutter to retain the atheroma materials severed from the blood vessel walls. The disclosures of both of the co-pending applications are incorporated herein by reference.
U.S. Pat. No. 3,614,953 issued to Moss discloses a drill for clearing obstructions in arteries. The drill disclosed is carried at the distal end of a flexible drive shaft which is disposed within a pair of concentric flexible tubes. The drill bit is positioned such that its tip portion extends slightly beyond the distal end of the outer tube. Moss contemplates inserting the cutter with the cutting face exposed After the catheter has been positioned, the drill is advanced within the artery while the bit is rotated at approximately 24,000 RPM. A pair of pipes 15 and 16 communicate with inner tube 2 and outer tube 1, respectively to introduce and remove a saline solution from the vicinity of the drill bit. Saline solution is fed via a pipe and the inner tube past the flats on the bit to the cutting face and withdrawn via the outer tube and a second pipe 16. The withdrawn saline solution carries a substantial portion of the fragmented deposits loosened by the rotating bit. However, the drill bit disclosed by Moss always extends outside of its housing and does not move relative to the housing, therefore increasing the risk of traumatizing the vessel through which it passes. Additionally, it does not recognize the advantages of utilizing a guide wire when possible to substantially reduce the risk of perforating the vessel walls. Further, its vacuum-based fragment removing system is unnecessarily complicated and a non-optimal bit design is disclosed.
U.S. Pat. No. 4,445,509 discloses an alternative drilling device for removing obstructions in blood vessels. A cutting tool is mounted at the end of a flexible drive shaft which transmits torque from a motor mounted on its proximal end. The cutting tool is inserted into the blood vessel through a guiding catheter using conventional angioplasty insertion techniques. However, the cutting tool is completely exposed in this embodiment, thereby greatly increasing the risk of traumatizing the vessel. A channel is incorporated into the drive shaft and the cutting bit for systematically removing the cutting debris.
Therefore, a primary objective of the present invention is to provide an atherectomy device particularly well suited for removal of extended atheroma and thrombus-type occlusions.
Another object of the present invention is to provide an end-bladed atherectomy device that is both safe and efficacious for the removal and collection of stenosis materials such as atheromas and thrombus.
Another object of the present invention is to provide an atherectomy device capable of retaining most or all of the removed atheroma materials.
Another object of the present invention is to provide an atherectomy device capable of removing stenosis materials from a wide variety of vessels, including peripheral and coronary arteries.